Thanks for all the replies!
It is a rather interesting conundrum, and as Delta-Yankee mentions google will only get you so far with this type of "before internet" question.
Unless someone has transcribed original documents across to the WWW the truth is probably in a box file at Kew or somewhere.
I agree with DY's analysis of how such a system might work, and although I can find photographs of German aircraft with IR sights on them, I can find none of so equipped allied aircraft. (Turbinlight being the only forward facing search light that I am aware of being used operationally, not counting the camouflage experiments I have read of)
I also wonder how long it would have taken the Germans to discover the nature of these lamps and exploit them, as they did with so much of the Allied airborne technology (and vice versa)- and whether this IR arms race would be known to modern historians
There does seem to be some basis to this rumour and I will have a mosey across to the mil forum and look up this Regle fella. (Thanks Tyres)
(they can be a bit rough over there though so I will tread carefully!)
On the subject of Blue formation lights, The Tornado F3 had them on the wings out near the trailing edge of the tips, the lenses were always cracking on them though so we seldom saw them used. If the Puma sported them as well it must have been the European equivalent to the American "Slime lights" or Low Intensity formation lights that abound these days.